Sunday, 25 September 2011

Just say no to polished seat lugs

This is my first, and probably last, polished stainless seatlug.

It's not that it was terribly technically challenging to do - the lug prep, mitering, and brazing were not so terribly different to what I normally do with a seatlug, except perhaps the degree of care in mitering the seat stays just so, and minimising the fillet when brazing them into place.

No, the real difficulty is the incredible amount of time it takes to file, sand, and finally polish this lug. Then, just when you think it's pretty good, you braze the seat stays in place and have to go back to 240 grit. Not to mention that it's practically impossible to get anything in between the stays - I'm seriously considering attaching emery to large matchsticks to get in there.

This one (Keith's) is probably at 80%. I've got more work to do under and between the seat stays. I'm very happy with the way the stay attachment has worked out - I think that should relatively easy to mask.

If only it didn't look so good!

I'll do a dozen crowns and headlugs before another seat lug. They're just easy to do - straightforward convex surfaces with plenty of room to swing a file.

Tuesday, 20 September 2011

Seat stays

It's always fun when those last two tubes get mitered up, ready to go on. The frame goes from a collection of tubes to an identifiable frame.

So this is the setup I've decided to use for the seatstay mitering. They join just a tad more aft than what I usually do - this will make the gap between them a tad (that's an important technical term - a little more than a squidge, but less than a mite) less than usual.

The plan is to make a silver preform and put this inside the tube, then heat and flow it out. This way I end up with minimal fillet on the outside (so I can polish the lug and have a maskable line), and a decent fillet on the inside, for a nice strong join.

I used just two tools to construct these fillets - a hacksaw and my 300mm half round second cut file.

Oh, and yes, that is a hair elastic holding the seat stays in position.

Wednesday, 14 September 2011

My other bike

Apologies to Keith, but this weekend is the annual Ducati owner's club concourse. This year the competition for the 2V monster trophy promises to be pretty fierce.

So I've spent the last week or so prepping my little duc 695, rather than working on Keith's frame.

It's been modified a bit since I bought it, but rather than just adding piles of carbon bling, I've kept the modifications purely functional. The biggest change I made was fitting superbike forks and brakes. The forks came off a 998, and necessitated fitting clipon handlebars and a fair bit of machining work to fit. After I'd swapped the springs for the correct ones to suit me and my monster, the ride is fantastic. I also swapped my brake calipers, master, and rotors for larger 320mm ones with four pistons per caliper. It handles like a dream.

The prep here involved painting the (originally chrome) headlight surround satin black, and removing the original handlebar mounts from the top triple clamp, then painting it satin black as well. Not to mention many hours of patient cleaning and polishing.

Most people simply buy a replacement triple when they do the fork upgrade. I prefer to work with what I have. I'm really happy with the way the original triple has come up. The front looks really cool and purposeful now, with the damping and preload adjusters for the forks poking through. The bar position with the clipons is much better than the original bars, which were rather too high for my tastes.

I kinda like this photo. It's gratifying to see the reflection of my neighbour's house in my tank :)

The 695 is notorious for running very lean from the factory - this ensures it passes strict European emissions tests (a good thing), but does mean the cylinders run rather hot. The paint on my cylinders and heads had gone gooey, and on the front head the gooey paint had picked up lots of road grime, looking really awful.

The exhaust header also went very rusty.

I've removed much of the gooey filthy paint from the front head. At some point I'll have to pull the heads and cylinders off the motor and bead blast the remaining paint, then respray them. This will do for now though.

I thought my headers would have to be replaced, but much elbow grease with scotchbrite pads and WD40 had them looking like new again.